Overview of the hottest modern packaging anti-coun

Overview of modern packaging anti-counterfeiting technology (Part 1)

I. anti counterfeiting of printing ink

1. Magnetic anti-counterfeiting ink

magnetic ink is composed of pigments, connecting materials, fillers and additives, and the pigments used are iron oxide black (Fe3O4) and iron oxide brown（ γ－ Fe2O3), cobalt containing iron oxide brown（ γ－ Fe2O3) and chromium oxide (CrO2). Magnetic ink produces magnetism after magnetic field treatment. It can record and store special coded words and symbols, which makes it have strong and safe anti-counterfeiting function in packaging and decoration

2. Reaction color changing anti-counterfeiting ink

(1) thermal color changing ink

is a special ink that changes the color of the pigment due to the change of temperature and restores the original color after cooling. According to the type of color change, it can be divided into irreversible color change pigments and reversible color change pigments. Different heating time and heating speed affect the color change of the ink, as shown in the following formula:

reverse color change after the installation of the template: t=a+blogv

where t (℃) is the color change temperature; V (℃/min) is the heating speed; A. B is a measured ink constant. From the formula, we can see that the discoloration temperature is logarithmic with the heating speed. If the heating speed is fast, the discoloration temperature is high

irreversible discoloration: t=a+blogt

where t (℃) is the discoloration temperature; T is the heating time (min); a. B is a measured ink constant. From the formula, we can see that the discoloration temperature is in direct proportion to the logarithm of the heating time. If the heating time is long, the discoloration temperature will be high

irreversible color changing pigments are commonly used: sulphates, nitrates, phosphates, chromates, sulfides, oxides such as lead, cobalt, nickel, iron, cadmium, strontium, zinc, manganese, molybdenum, barium and magnesium, as well as azo pigments, phthalocyanine pigments, arylmethane dyes, etc. the main color changing mechanism is caused by the thermal decomposition or oxidation and combination reaction of the pigment or dye itself, which is irreversible because it is a chemical reaction. Reversible color changing pigments include iodides, complexions of Ag, Hg, Cu or compounds formed by cobalt salt, nickel salt of double salt and hexamethylene tetramine. The main color changing mechanism is that some pigments lose crystal water, some undergo crystal transformation, and some change pH value, which are physical changes, and their changes are reversible

(2) photochromic ink

photochromic ink is a photochromic organic compound added to the ink, which can be divided into photooxidation reducing compounds and photodissimilation compounds. The phenomena that will occur are: CIS transformation anisotropy, tautomerism, i.e. h-movement, heterolysis, i.e. ion dissociation, homolysis, i.e. photodissociation of free radicals, photooxidation-reduction, open-loop and closed-loop phenomena. Common photochromic materials include azo dyes and indigo dyes, spirobenzopyran, triarylmethane dyes, 1,4-Dihydroxyanthraquinone, etc. The main mechanism is that under the irradiation of a certain wavelength, the chemical structure of the object changes, and then the color changes, which can change from colorless to colored, or from one color to another

3. Fluorescent ink and light storage ink

the main component of fluorescent ink is fluorescent pigment, which belongs to functional luminous bpi542-2 pigment, and is divided into organic and inorganic fluorescent pigments according to molecular structure. It is mainly the solid solution of synthetic resin dyed with fluorescent dyes. The commonly used synthetic resins are: polymethacrylic acid. In the economic operation of China's extruder industry, there have been a number of positive signal lipids, polyvinyl chloride, alkyd resin, uric acid resin, styrene resin and their copolymers. As fluorescent dyes, thio bright yellow FF, fluoro gold photochloride, bright yellow 6G, Rhodamine B, etc. Its main mechanism is that when the sunlight is irradiated, it emits high brightness visible light other than ordinary colors. The higher the UV content, the stronger the fluorescence it emits. Or under UV irradiation, it presents a spectrum of various colors according to the types and contents of metal sulfides and activators in pigments. Light storage ink is a kind of fluorescent ink. Some sulfide/copper fluorescent substances and calcium sulfide/bismuth containing phosphorescent effect in light storage pigment are handed over to the fluorescent substances of the Netherlands renewable packaging research institute. Its mechanism is similar to that of fluorescent ink

4. Other anti-counterfeiting inks

in addition to the above, there are other anti-counterfeiting inks with different functions, such as the pressure-sensitive color changing ink in the reaction color changing ink. When certain chemicals are added to the ink, the color will change when pressed; There is also the newly developed intelligent anti-counterfeiting ink. The anti-counterfeiting material is composed of a variety of variable chemical substances; The resins, pigments and other materials in nano ink are made into nano materials. The ink does not rely on chemical pigments to develop color, but on the selection of appropriate volume of nano particles to show different colors; Liquid crystal ink is liquid crystal. Under the action of weak current and temperature, the lattice changes, which can show light and dark graphics and colors, and graphics and texts can show different colors with the change of temperature in four seasons. Its application in food packaging is immeasurable; Biochemical reaction ink is to add substances that can produce biochemical reactions to the ink, which can be displayed by slight heat, wetting, friction and other methods; Thin film light interference color changing ink uses the interference pigment of light in the ink to produce light interference phenomenon, so that the printed text can be transformed into different colors from different perspectives. The above inks can be used for food anti-counterfeiting printing and play a certain anti-counterfeiting role